Environmental Engineering

The water resources and environmental engineering group performs multidisciplinary research in the areas of surface and groundwater hydrology, land-atmosphere interactions, hydrometeorology, contaminant transport and remediation in aquatic and soil environments, watershed biogeochemistry, solar and microbial fuel cell energy production. The faculty interacts with a broader group of faculty members that are affiliated with the Environmental Engineering Program and also works closely with the Center for Environmental Science and Engineering.

Featured Projects

Collaborative Research: SitS NSF UKRI: Decoding Nitrogen Dynamics in Soil through Novel Integration of in-situ Wireless Soil Sensors with Numerical Modeling

Team holds their sensors for SitS research project.

Sponsor: National Science Foundation

Principal Investigator: Guiling Wang, Yu Lei, Karl Guillard, MD Shaad Mahmud (University of New Hampshire)

Period: 01/01/2020 - 12/31/2013 

Budget: $800,000

Project Abstract

Excess nitrogen leaching from agricultural and horticultural lands into waterways is a long-standing challenge for agricultural sustainability and environmental protection. An effective approach to improve the water/fertilizer use efficiency is through precision farming practices guided by real-time monitoring and near-term forecast of crop irrigation and fertilization needs. 

By targeting two critical soil signals: nitrogen species (ammonium and nitrate) and soil moisture, this US-UK SitS collaborative project will develop innovative hydrogel-coating solid-state ion-selective membrane (HS-ISM) soil nitrogen sensors, numerical models of rhizosphere nitrogen cycle through both lab-scale and field tests. This project will, for the first time, achieve high-resolution in-situ nitrogen profiling and predict the rhizosphere nitrogen dynamics under different weather and farming practices.

A Bottom-up Approach to Design of Chemical Soil Stabilization Using Thermodynamic Modeling

Map of clay soils in the United States

Image from https://geology.com/articles/soil/

Sponsor: National Science Foundation

Principal Investigator: Maria Chrysochoou

Period: 08/15/2017 - 07/31/2020 

Budget: $272,694



Project Abstract

Clay soils are present in large parts of the United States, such as Texas, Oklahoma, Kansas and others. Since clay soils are unsuitable as foundations for construction of highways and other structures, various stabilization techniques are employed to improve their properties. Chemical soil stabilization using lime and Portland cement is among the most widely applied approaches. Typically, design of soil stabilization requires the performance of lab scale treatability studies in order to determine the optimal chemical dosage, and there is still limited ability to predict the long-term behavior of stabilized soils over months and years. Models that describe the chemical reactions within stabilized clays over time are currently lacking and are necessary to improve our predictive ability. Accordingly, the overarching goal of this project is to generate the fundamental kinetic and thermodynamic models that will quantitatively describe the evolution of the chemical reactions between clay minerals and common stabilizers (lime, Portland cement). The long-term vision of the project is to utilize the models to predict long term behavior of stabilized clays and inform the mix design, minimizing the need to conduct treatability studies. In addition, the models will be tools for assessing the behavior of chemically stabilized soils under different scenarios (e.g. increased carbonation or impact of acidification).

Model development will be done for eight different combinations (pure kaolinite with different particle sizes, pure Na-bentonite and one soil stabilized with quicklime and Portland cement) that will be provide a) fundamental data for pure minerals; and b) insight into the applicability on a real soil. Three different techniques (quantitative X-ray Diffraction, thermogravimetric and differential thermal analysis and Nuclear Magnetic Resonance) will be employed to monitor the solid phase composition in pure and reactive systems over time, utilizing advanced spectra deconvolution techniques. The generated data will be used to fit kinetic models for the pozzolanic reactions of each clay mineral. In addition, monitoring of pore solution composition will allow to conduct both forward and inverse thermodynamic modeling to predict the system stability and potential evolution. Due to the multi-disciplinary nature of the project, a parallel goal is to provide training opportunities integrating geotechnical engineering, geochemistry and materials science. Specifically designed modules with project-related multi-disciplinary concepts will be designed and integrated in regularly offered teaching and outreach activities at UCONN, providing a sustainable platform for continuous exposure of wide student audiences and expanding existing initiatives, from K-4 soil modules, to an ASCE webinar for professionals, new undergraduate courses and a distance learning Masters of Engineering. Engagement across three professional societies (chemistry, environmental and civil engineering) will result in cross-fertilization and wide dissemination of project results.

Water and Food Security PIRE

2019 Site Visit

Sponsor: National Science Foundation

Principal Investigator: Prof. Emmanouil Anagnostou

Period: 01/01/2016 - 12/31/2021



Project Abstract

How do relationships between scientists, farmers, water managers, and authorities influence the production, dissemination, and outcome of new scientific knowledge? This project establishes an international research and education partnership to promote a political-institutional model of science that links sociological and engineering methods in a people-centered approach to the human-climate-water-agriculture-energy nexus in the Blue Nile basin (BNB), Ethiopia.

The project is a multi-year collaborative endeavor that will run from 2016 to 2021. By the end of the project, the research team will have crafted state-of-the-art tools to help smallholder farmers make practical decisions about water, crops, and fertilizers and ultimately gain more secure access to food and water in the face of increasingly challenging climatic extremes.

Addressing Aging Infrastructure: From Components to Networks

Aging InfrastructureSponsor: Graduate Assistance in Areas of National Need (GAANN)

Principal Investigator: Varies

Period: Varies

Budget: Varies


Project Abstract

The Civil and Environmental Engineering Department at the University of Connecticut invites Civil Engineering PhD applicants to apply for a GAANN Fellowship supported by the US Department of Education in the area of addressing aging infrastructure. GAANN fellows will be engaged in cutting-edge research in several areas, including, but not limited to, “big data”, advanced sensors, optimization of transportation networks, monitoring and feedback loops to control wastewater treatment processes, new components for bridge repairs, and prediction modeling. Fellows will develop research through collaborations with faculty and stakeholders.

Impact of Urbanization on Organic Carbon-Metal Interactions and Trophic Transfer in Streams

Organism Diagram

Sponsor: National Science Foundation (NSF)

Principal Investigator: Timothy Vadas

Period: 02/01/2015 - 12/31/2021 

Budget: $500,000


Project Abstract

In an increasingly urbanizing landscape, the negative impact of metals from both stormwater and wastewater effluent on organisms in streams will continue to rise. While the focus of most metal bioavailability models for stream organisms is on ambient exposure to dissolved metal phases, this proposed research also addresses the integral role of attachment and ingestion of organic matter in controlling bio-uptake of metals. At the ecosystem scale, the biodynamics of metal uptake and retention relate to both metal and organic matter characteristics, exposure patterns and feeding behavior of stream organisms. Assessment of metal speciation and size distribution as well as organic matter characteristics as related to metal uptake is required knowledge for the development of ecosystem level exposure assessment models that are useful for establishing management strategies for streams. In addition to the proposed research, the education plan will support the training of 1 M.S. and 1 Ph.D. student and at least 2 undergraduate researchers. Enhanced student training will focus on additional coursework in related disciplines and communication skills to promote interdisciplinary research in the future. Educational modules will be developed for K-12 classrooms according to State education guidelines. These modules will be disseminated through the DaVinci program at the University of Connecticut to broaden their reach beyond an individual classroom. A significant aspect of this project will be integrating ecology and environmental engineering across all levels of education through a focus on basic understanding and communication across disciplines: Several interdisciplinary problem-based learning exercises will be developed for university level education and K-12 education modules related to stream impairment will be developed and distributed widely.

This plan addresses the research and education challenges associated with developing more effective management strategies for impaired streams in urban areas. The existing framework to assess and manage impaired streams does not address the dynamic and unique conditions present in streams. Metals such as copper and zinc are both necessary and toxic depending on the concentration, and are one of the most common causes of impairment. However, the strong interaction with organic matter across all size ranges and differences in exposure patterns of the effluent and stormwater sources of impairment are dramatic. Total metal loads are not necessarily good indicators of bio-uptake and both metal lability and ingestion of the different organic-metal particulates must be considered. In order to address the stream impairment issues associated with different metal sources, a more complete understanding of metal bio-uptake under urban stream conditions is required. To accomplish this, the following objectives and approach will be: 1) Quantify the variability of metal speciation and size distribution in different stream source waters across space and time: Automated samplers will collect time interval and flow-weighted samples of effluent and stormwater runoff, respectively, at impaired sites across a range of urban to suburban sites. Samples will be separated into size fractions relevant to biotic uptake and analyzed for total metals, organic matter, colloidal metal and organic matter size distribution, and organic matter optical, chemical and metal binding characteristics. 2) Identify metal speciation and size distribution predictors of biological uptake in primary producers and higher trophic level organisms and the dependence on metal loading dynamics: Metal uptake and attachment will be analyzed as a function of size distribution and chemical characteristics of the organic matter in different source waters. Biodynamic modeling will assess the net metal uptake into algae and subsequent transfer to higher trophic level organisms. These will be examined under exposure regimes that mimic the stream, e.g. with different ratios of source water to stream water for effluent sources and varying exposure concentrations for stormwater runoff.

Understanding the Decrease of Precipitation Extremes at High Temperature and its Implications

rain on road

Sponsor: National Science Foundation (NSF)

Principal Investigator: Guiling Wang

Period: 06/01/2017 - 05/31/2020 

Budget: $542,905


Project Abstract

Recent decades have seen an increasing trend in extreme precipitation intensity (EPI) over much of the globe including the continental US. The trend is generally regarded as a consequence of increasing temperature, as for the same relative humidity warmer air holds more precipitable water than colder air. Apart from the trend, EPI shows similar variation during weather-related temperature fluctuations between warm and cold days, as extreme precipitation events on colder days tend to be less intense than their counterparts on warmer days. But in day-to-day temperature fluctuations the increase of EPI with temperature only holds up to a point, beyond which intensity falls off with further increases in temperature. It is thus of interest to understand why EPI increases with temperature up to a threshold value and then decreases in day-to-day variability, what determines the temperature at which EPI peaks, and how the EPI-temperature relationship changes as a result of long-term increases in temperature.

The PI hypothesizes that the reduction in EPI at the highest temperatures is a consequence of the effect of temperature on the moisture difference between air in convective clouds and the ambient air surrounding them. Rising air in convective clouds is generally saturated with water vapor while ambient air surrounding the clouds is not, thus the vigor of clouds is suppressed when drier ambient air is mixed into them. The suppressing effect of ambient air mixed into clouds increases with temperature if the moisture difference between cloud and ambient air increases with temperature, an increase which is expected under reasonable assumptions including a minimal change in ambient relative humidity. Work in this project examines the role of this moisture deficit mechanism in suppressing the development of deep convective clouds from shallow clouds, thereby reducing extreme precipitation at high temperatures. The work also considers the change in the EPI-temperature relationship that occurs as climate warms, with the hypothesis that the relationship remains qualitatively the same but the threshold value shifts to progressively higher temperatures. Additional work considers the possible implications of the moisture deficit mechanism for drought. The work is carried out through a combination of observational analysis and climate model simulations.

The project has broader impacts due to the severe consequences of extreme precipitation for human activities and the need to understand how the threats posed by extreme precipitation will evolve in a changing climate. The PI is also engaged in a variety of outreach activities at local schools, including a 5-day workshop for middle- and high-school math and science teachers. In addition, the project supports a graduate student and a postdoctoral researcher, thereby providing for the development of the workforce in this research area.